Generally, FBG ID reflector is of standard SC/LC type connector structure, in which a special FBG is encapsulated in a ceramic ferrule. At T&S, the reflector can also be SC pigtail structure or stainless steel tube package type. The FBG ID reflector is a low-cost specific band reflector mounted on the optical network unit (ONU) side. It reflects light pulses from the OTDR on the fiber line terminal (OLT) side nearly 100%, while the working bands of the passive optical network (PON) are transmitted normally.
The OTDR determines whether the fiber is normal by detecting the signal reflected by the reflector. When the reflected signal is lower than the normal value, the line loss is considered too large; when the reflection value is almost zero, then the fiber line is broken.